Patent Application
20250109055
This application claims priority to Chinese Patent Application No. 202211358216.6 filed Nov. 1, 2022, Chinese Patent Application No. 202222929439.5 filed Nov. 1, 2022, and Chinese Patent Application No. 202322399577.1 filed Sep. 4, 2023, the disclosures of which are incorporated herein by reference in their entireties.
The present application relates to the field of glass tempering, for example, a glass tempering furnace and method.
Glass, as a transparent or translucent amorphous material, exhibits unique properties during heat transfer. Glass is a structure with short-range order and long-range disorder. Glass is transparent or translucent to visible light and infrared light. When receiving external heat, the internal of the glass generates high-frequency electromagnetic radiation. This heat transfer process is called photon conduction. At room temperature, photon conduction in transparent glass accounts for approximately 10% of the total heat transfer. As the temperature increases, the effect of photon conduction increases, and the volumetric radiation occurs inside the glass.
Ordinary transparent glass has a high emissivity and can absorb thermal radiation well. Applying a thin film having low emissivity property onto the surface of ordinary glass creates Low-E glass. The most significant feature of Low-E glass is high reflectance for far-infrared radiation, low emissivity for near-infrared radiation, and high transmittance for visible light. This means that after using Low-E glass in buildings, the visible light portion of sunlight can penetrate, providing daylighting, while most of the infrared radiation that can generate heat is blocked outside the window. Due to surface modification of Low-E glass, many problems arise during a tempering and heating process.
Compared with ordinary glass, tempered glass is considered as safety glass. Tempered glass is actually prestressed glass. To enhance the strength of glass, chemical or physical methods are typically used to create compressive stress on the surface of the glass. When subjected to an external force, the glass first offsets the surface stress, thereby increasing the load-bearing capacity and enhancing the resistance to wind pressure, temperature variations, and impact.
The tempering of glass is divided into “physical tempering” and “chemical tempering.”
Physical tempering involves heating ordinary flat glass in a furnace to near its softening temperature (about 600° C.), eliminating internal stress by deformation of the glass, removing the glass from the furnace, and blowing high-pressure cold air onto both sides of the glass by multiple nozzles to rapidly and uniformly cool the glass to room temperature, thus producing tempered glass.
Chemical tempering, which enhances the strength of glass by altering chemical composition of the surface of the glass, is typically tempered by using an ion exchange method. The method involves immersing silicate glass containing alkali metal ions into molten lithium (Li+) salt and making Na+ or K+ ions on the surface of the glass exchange with Li+ ions to form a Li+ ion exchange layer on the surface of the glass. Since Li+ ions have a smaller expansion coefficient than Na+ or K+ ions, the outer layer contracts less while the inner layer contracts more during cooling. As a result, upon reaching room temperature, the glass is subjected to tension in the inner layer and compression in the outer layer, similar to the effect observed in physically tempered glass.
The present application discusses the device involved in physical tempering, namely a tempering furnace.
From the perspective of heat transfer, the heating process of glass in the tempering furnace involves radiation heat transfer, convective heat transfer, and thermal conduction.
Radiation heat transfer: Radiation is ubiquitous. When a piece of cold glass enters the heating furnace section of the glass tempering furnace, various heating elements, furnace wall insulation materials, and ceramic rollers emit radiant heat to heat the glass. Waves have two forms, “absorption+penetration”, for the heated object. Only when the waves are absorbed, can the object be heated. In terms of the spectrum curve of glass, due to the composition of the glass, the glass appears as “peaks and valleys” on the infrared transmission curve, rather than a straight line. Corresponding to the “valleys” is the range of wavelengths that the glass can absorb. The wavelengths that the glass can absorb are not uniform.
Convective heat transfer: In the production process of tempered glass, several convective heat transfer modes exist.
Heat conduction: The upper surface of the glass does not come into contact with components in the furnace, and only the lower surface of the glass contacts ceramic rollers. The ceramic rollers are primarily made of quartz with the addition of auxiliary materials, resulting in a thermal expansion coefficient close to zero and a low thermal conductivity. The contact (theoretically linear contact) area between the ceramic rollers and the glass is small, so thermal conduction is not the primary mode of heat transfer throughout the entire heating process. Less than 10% of the heat absorbed by the glass in the heating furnace section comes from thermal conduction. However, when cold glass initially enters the furnace, contact between the lower surface of the cold glass and hot ceramic rollers causes the glass to warp and jitter. This should be noted.
In the related art, the heat source in a radiant-type tempering furnace in the industry that is heating glass comes from electric heating elements located on the top and bottom of the furnace. These electric heating elements are typically made of nickel-chromium resistance wires. Each electric heating element is either mounted in a metal tube to radiate heat in the form of a radiation tube or sheathed on a heat-resistant ceramic tube with which a resistance wire radiates heat into the furnace. The glass is usually placed flat on drive rollers made mainly of heat-resistant ceramics and is fed into the furnace by the rotation of the rollers. To temper large-sized flat glass, electric heating elements inside the furnace are generally arranged as densely as possible on the top and bottom of the furnace. When the glass is fed into the furnace at room temperature, it undergoes radiant heat transferred from the electric heating elements and heat conducted from the drive rollers in contact with the glass. Since the furnace temperature is generally around 700° C., the drive rollers have a high temperature, resulting in significant heat transfer to the glass through conduction. This causes the temperature of the lower surface of the glass to be higher than that of the upper surface of the glass, leading to non-uniform temperature distribution along the thickness direction of the glass and resulting in bending and warping of the edges of the glass. At this time, the gravity is concentrated in the middle of the glass, forming roller marks. Non-uniform heating also causes white spots to appear in the central part of the glass. This problem becomes even more serious when the substrate of laminated glass is tempered.
Low-E glass is formed from ordinary glass whose one side is coated. During tempering, to avoid damage to the coated surface by the rollers, the glass is fed into the tempering furnace, with the side with the coating facing upwards. From a heat transfer perspective, to ensure uniform heating of the glass, it is required that the rate of heat transfer from the upper surface of the glass to the interior of the glass and the rate of heat transfer from the lower surface of the glass to the interior of the glass remain consistent during heating. The electric heating elements primarily heat the Low-E glass through radiation. Infrared radiation projected onto the object creates a noticeable thermal effect and is a major component of heat rays. The emissivity of the Low-E glass is non-uniform, with the lower surface of the glass having a high emissivity of around 0.90. After a large amount of heat is absorbed, the temperature of the lower surface increases, and the effective thermal conductivity increases so that the heat is further transferred to the inside. On the coated side, the emissivity typically ranges from 0.10 to 0.23. The coating layer reflects a large amount of infrared radiation, making it difficult for thermal radiation to transfer from the coated surface to the interior of the glass.
In the related art, to uniformly heat the surface of glass, it is necessary to completely cover the surface of the glass by using heating elements. This surface heating method is characterized by applying at least 50% of the heat from the heat source to the surface or near-surface layer of the object being heated. The heating method in the related art has limitations. For example, in the case of heating using chromium-aluminum-cobalt metal resistance wires, the maximum load on the heater surface at 1000° C. can only reach 60 kW/m2, whereas the radiative power density of a comprehensive black radiator at the same temperature can reach 149 kW/m2. The resistance wire heating in the related art involves extremely dense heater arrangement. This arrangement shortens the service life of the heating elements.
During a glass heating process, the highest heating temperature of a nickel-chromium heating element in the related art is 1150° C. while the highest heating temperature of an iron-chromium heating element in the related art is 1400° C. In view of furnace temperature and costs, the related art mostly uses electric heaters made of a Ni—Cr alloy. Based on the correspondence between the temperature of a heat source and the wavelength of radiation, the wavelength radiated from a heater at 1150° C. is 2.04 micrometers. Considering the furnace temperature and the tempering temperature of glass, the heating temperature of a resistance wire inside an electrically heated tempering furnace is lower than 1150° C., typically between 800° C. and 900° C. The corresponding heat source radiation wavelength is between 2.47 μm and 2.7 μm. This wavelength range is relatively narrow, and not all glasses absorb radiation within the range of 2.47 μm to 2.7 μm.
The related art is gradually beginning to use an infrared radiator to uniformly heat transparent glass to increase the heating speed of the glass and shorten the heating time. However, this method has the disadvantage that it cannot ensure uniform radiation across the entire surface of a glass, resulting in a projection of the intensity distribution of the infrared radiation source formed on the surface of the glass that requires to be heated.
To address this problem, the glass industry has introduced “forced convection heat transfer technology” into tempering furnaces. Adding upper forced convection in a roller-type tempering furnace is beneficial for symmetric heating of glass. Moreover, for Low-E glass, the presence of a coating significantly increases the heating time. Increasing forced convection can shorten the heating time and reduce the furnace temperature, greatly beneficial for reducing the coating loss and improving the production efficiency. Adding forced convection to the lower part is unnecessary. In a roller-type tempering furnace, due to unavoidable heat transfer from the roller and natural convection in the lower part, the lower part is heated too quickly and the glass is upturned to form white mist in the middle part. More importantly, the middle part is heated too fast. When the center of the glass reaches the tempering temperature, the lower surface is already overheated and too soft, resulting in pits or roller track marks on the lower surface of the glass which is a headache. This contradiction will become more prominent if forced convection is added to the lower part.
However, in glass tempering in related technologies, especially in the tempering of coated glass and Low-E glass, there are still problems in the early stage of glass entering the furnace, such as the temperature of the lower surface of the glass rising too fast, the temperature of the upper surface of the glass rising too slowly to lead to upward warping and vibration of the glass, extremely dense distribution of heating elements in the electric heating tempering furnace to lead to too short life and slow heating speed, and uneven heating phenomenon and high energy consumption caused by the infrared radiation heating technology applied to the tempering furnace.
The present application proposes a glass tempering furnace and a glass tempering method that can rapidly and uniformly heat glass and that are suitable for tempering of ordinary glass, particularly coated glass and Low-E glass.
The present application provides a glass tempering furnace. The glass tempering furnace includes a preheating furnace section, a heating furnace section, and a soaking furnace section. The preheating furnace section has a feed port. A general smoke vent is formed at the feed port. The preheating furnace section is divided into a plurality of sections along the glass traveling direction. Each section has a smoke suction port and a smoke ejection port. The heating furnace section has a plurality of infrared burners. Each infrared burner is a porous medium burner. The preheating furnace section is configured to suck smoke from the heating furnace section through the smoke suction port and eject the sucked smoke to the preheating furnace section through the smoke ejection port. The soaking furnace section is disposed after the heating furnace section along the glass traveling direction. A plurality of air ducts are disposed in the soaking furnace section and configured to generate horizontally parallel airflow on the upper and lower surfaces of glass.
The present application also provides a glass tempering method. The method is applied by the glass tempering furnace. The method includes manually (or automatically) laying and placing the glass on a side cloth table; carrying the glass on a plurality of drive rollers to the preheating furnace section and preheating the glass in the preheating furnace section; carrying the glass to the heating furnace section and heating the glass in the heating furnace section to a set temperature of 600° C. to 640° C.; and carrying the glass from the heating furnace section to the soaking furnace section and heating the glass and homogenizing the temperature of the glass by circulating gas passing the upper and lower surfaces of the glass.
In the description of the present application, it is to be understood that the orientation or position relationships indicated by terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “above”, “below”, “front”, “back”,” “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc. are based on the orientation or position relationships shown in the drawings, merely for facilitating description of the present application and simplifying description, and do not indicate or imply that the apparatus or element referred to has a specific orientation and is constructed and operated in a specific orientation, and thus it is not to be construed as limiting the present application.
In addition, a feature defined as a “first” feature or a “second” feature may explicitly or implicitly include one or more of such features, which are used for distinguishing and describing the features, and there is no order or importance. In the description of the present application, “multiple” means two or more unless otherwise noted.
In the description of the present application, it is to be noted that unless otherwise expressly specified and limited, the term “mounted”, “connected to each other” or “connected” should be construed in a broad sense as securely connected, detachably connected or integrally connected; mechanically connected or electrically connected; directly connected to each other or indirectly connected to each other via an intermediary; or intraconnected between two components. For those of ordinary skill in the art, specific meanings of the preceding terms in the present application may be understood based on specific situations.
Referring to
In some embodiments of the present application, the preheating furnace section 100 has a feed port. A general smoke vent 120 is disposed adjacent to the feed port.
In the related art, the general smoke vent is generally disposed on a heating section. In the present application, the smoke vent of the heating section is moved forward to the position of the feed port of the preheating section. On the one hand, smoke is moved from the heating section to the preheating section to serve as the heat source of the preheating section. On the other hand, the smoke vent is spaced a certain distance from the heating section, reducing the impact of smoke release on the temperature field of the heating section.
In some embodiments of the present application, the preheating furnace section 100 is divided into multiple sections along the glass traveling direction of the glass 20. Each section has a smoke suction port 130 and a smoke ejection port 140. The smoke suction port 130 is configured to suck smoke from the heating furnace section. The smoke suction port 130 is configured to suck smoke from the heating furnace section 200. The smoke ejection port 140 is configured to deliver the sucked smoke to the preheating furnace section.
In the related art, utilizing a “chimney effect”, smoke generated by a heating section of a glass tempering furnace is released by a smoke suction port disposed at the entrance of the furnace and a chimney connected to the smoke suction port.
In the present application, the preheating furnace section 100 is disposed before the heating furnace section 200. The general smoke vent 120 of the whole equipment is disposed at the entrance of the preheating section. Moreover, along the glass traveling direction, a smoke suction port 130 is disposed on each section of the preheating furnace section 100, the smoke in the furnace is sucked out though each smoke suction port 130 by a fan, and then the sucked smoke is delivered to the furnace through the smoke ejection port 140 of each section of the preheating furnace section 100, so that the internal gas circulation in the preheating furnace section 100 is established. In this manner, it is achieved that the pressure in the furnace maintain a preset target of “slightly positive pressure”, and then it is achieved that the gas in the furnace generally flows from the heating furnace section 200 to the preheating furnace section 100.
In an actual working process, each section of the preheating furnace section 100 has a smoke suction port 130. Smoke in the furnace can be sucked out through each smoke suction port 130 by a fan. In this manner, pressure in the heating furnace section 200 decreases so that pressure in the heating furnace section 200 is greater than pressure in the preheating furnace section 100. Meanwhile, smoke in the heating furnace section 200 enters the preheating furnace section 100 under the action of a pressure difference. Then the sucked smoke is delivered to the preheating furnace section 100 through each smoke ejection port 140. In this manner, smoke in the furnace generally flows from the heating furnace section 200 to the preheating furnace section 100 recurrently.
With the preheating furnace section 100, on the one hand, smoke in the heating furnace section 200 can be reused; on the other hand, the preheating furnace section 100 is divided into multiple sections, smoke is sucked out through the smoke suction ports 130 and delivered through the smoke ejection ports 140 so that the temperature of the glass 20 in the preheating furnace section 100 can rise in a stepped manner. Heat of the preheating furnace section 100 comes from smoke of the heating furnace section 200, and considering the continuous entry of the glass 20 as a cold source, the temperature of the drive rollers 101 of the preheating furnace section 100 is far lower than the temperature of the drive rollers 101 of the heating furnace section 200. In this manner, it can effectively avoid deformation (upward warping) and vibration caused by an excessive temperature difference between the upper surface of the glass 20 and the lower surface of the glass 20 due to excessive temperature of the drive rollers 101 in the initial stage in which the glass 20 enters the heating furnace section.
In the present application, the soaking furnace section 300 is disposed after the heating furnace section 200, which further ameliorates the temperature non-uniformity on the surface of the glass 20 in the heating stage and satisfies higher-standard uniformity requirements, thereby further improving the tempering quality of the glass 20, particularly satisfying tempering requirements of coated glass and Low-E glass with high-standard uniformity requirements.
In a conventional glass tempering furnace of the related art, it is necessary to address the problem of upward warping and vibration caused by non-uniform heating of the glass in the heating section at the initial stage. The glass tempering furnace 10 of the present application is completely different from a conventional glass tempering furnace in the related art. In the glass tempering furnace 10 of the present application, the preheating furnace section 100 is independently established, smoke in the heating section is used as the heat source, and the preheating section is independently established, cooling down the temperature of the ceramic rollers in the preheating section. The glass 20 is preheated in a forced convection manner, solving the problem of warping and vibration caused by non-uniform heating of the glass 20 in the initial stage.
In some embodiments of the present application, the preheating furnace section 100 is divided into three sections in the glass traveling direction. The preheating furnace section 100 is divided into a preheating-section upper furnace portion 102 and a preheating-section lower furnace portion 103. The preheating-section upper furnace portion 102 is disposed above the drive rollers 101. The preheating-section lower furnace portion 103 is disposed below the drive rollers 101.
Referring to
Referring to
In an embodiment, taking the upper 1 #as an example, the first smoke suction port 131 of the upper 1 #is connected to the suction port of a smoke suction fan. Smoke in the furnace is sucked out by the smoke suction fan. By dividing the pipeline into two, the sucked smoke is delivered to the first smoke ejection port 141 and the second smoke ejection port 142 of upper 1 #. Similarly, in lower 1 #, the second smoke suction port 132 is connected to the suction port of a smoke suction fan, and smoke in the furnace is sucked out by the smoke suction fan. By dividing the pipeline into two, the sucked smoke is delivered to the third smoke ejection port 143 of lower 1 #and the fourth smoke ejection port 144 of lower 1 #.
In some embodiments of the present application, multiple smoke ejection air knives 150 are disposed on upper and lower sides of the drive rollers 101 along the glass traveling direction in the preheating furnace section, and the smoke ejection air knives 150 on upper and lower sides of the drive rollers 101 are staggered with the drive rollers 101 in the height direction. The smoke ejection port 140 is configured to deliver the sucked smoke to the smoke ejection air knives 150.
Referring to
In some embodiments of the present application, the diameter of the air knife outlet 153 of each smoke ejection air knife 150 is contracted.
In some embodiments of the present application, an incrementer 160 is disposed in the preheating furnace 100. The incrementer 160 has a channel 161 with a Venturi structure. The channel 161 is connected to the air knife outlet 153 of each smoke ejection air knife 150.
Referring to
In the related art, a smoke ejection structure is typically a “circular hole staggered arrangement type” or a “slit-type” smoke ejection structure. The present application provides a structure with an “increment” effect, increasing the amount of ejected smoke and enhancing the heating efficiency.
Illustratively, referring to
In an embodiment, referring to
In some embodiments of the present application, the heating furnace section 200 is disposed after the preheating furnace section 100 along the glass traveling direction.
In some embodiments of the present application, referring to
In some embodiments of the present application, the heating furnace section 200 is provided with multiple infrared burners 210. Each infrared burner 210 is a porous medium burner.
The heating furnace section 200 of the present application uses a porous medium combustion technology mainly based on infrared radiation. Three heat exchange modes: convection, heat conduction, and radiation are used to make the temperature of the combustion area 219 approximately uniform and make the temperature gradient relatively stable. The heating furnace section 200 of the present application uses a porous medium combustion technology to construct a wideband infrared heating section to heat the glass rapidly and uniformly. In this manner, the glass tempering furnace of the present application is applicable to not only ordinary glass but also coated glass and Low-E glass.
The porous medium combustion technology enables stable combustion and a high volume thermal strength. Compared with free combustion, porous medium combustion has the advantages of high combustion rate, good combustion stability, large load adjustment range, large volume thermal strength, small burner volume, good gas adaptability, low pollutant discharge from smoke, wide combustion limit, and low combustible heat value.
In the art, a heating furnace uses gas fuel whose combustion is featured by free flame. This type of combustion requires a large space, has a large temperature gradient around the flame, and easily generates a high local temperature. Nitrogen oxide (NOX) generation becomes noticeable when the temperature is higher than 1500° C. Because of the highly toxic property of nitrogen oxide (NOx), reducing NOx emission is also very important.
Compared with conventional free-flame combustion in a heating furnace of the related art, porous medium combustion in the heating furnace section 200 of the present application greatly improves the combustion efficiency. In the combustion process, a porous medium plays a key role. Porous medium materials have the following features: superior heat transfer properties, forced gas flow in and out, separation and convergence, enhanced convection, uniform temperature distribution, and low temperature level, reducing pollutant emission; low volume density, namely low thermal inertia, enabling a rapid temperature rise during startup and quick adaptation to load changes; and being operable within a temperature range of 800° C. to 1200° C.
In some embodiments of the present application, each infrared burner 210 of the heating furnace section 200 uses a porous medium material as the main combustion component, and gas is burned in the porous medium material. The porous medium material of the present application is SiC. The radiation rate of SiC is about 0.9, far higher than the radiation rate of a common metal alloy heating material, and thus has a better radiation heating effect. Each infrared burner 210 of the heating furnace section 200 of the present application uses SiC as a porous medium material, improving the heating effect.
The heating furnace section 200 of the present application uses infrared burners 210 whose core technology is porous medium combustion.
In some embodiments of the present application, in the heating furnace section 200, the infrared burners 210 are staggered on upper and lower sides of the drive rollers 101 along the glass traveling direction.
Referring to
In the heating furnace section 200, the infrared burners 210 are staggered on upper and lower sides of the drive rollers 101 along the glass traveling direction so that the heating uniformity can be improved.
In some embodiments of the present application, airflow stirring devices 220 are disposed in the heating furnace section 200 and spaced from the infrared burners 210 along the glass traveling direction.
A drawback of infrared radiation is the inability to ensure uniform radiation across the entire surface of the object, resulting in a projected intensity distribution of the infrared radiation source on the surface that requires to be heated. The airflow stirring devices 220 are disposed in the heating furnace section 200 to cooperate with the infrared burners 210. The airflow stirring devices 220 are spaced from the infrared burners 210. The airflow stirring devices 220 can stir smoke in the furnace, avoiding local concentration of high-temperature smoke in the furnace and thus avoiding non-uniform furnace temperature; and enabling the stirred smoke to flow on the surface of the glass 20 at a preset speed and thus increasing convective heat transfer.
In an embodiment, referring to
In some embodiments of the present application, multiple air ducts 310 are disposed in the soaking furnace section 300 and configured to generate horizontally parallel airflow on the upper and lower surfaces of the glass 20. Specifically, the soaking furnace section 300 includes a receiving cavity 350 and air ducts 310. In an embodiment, the drive rollers 101 are disposed on the bottom wall 351 of the receiving cavity 350 and configured to drive the glass 20.
Glass “tempering” involves a “heating” process and a “cooling” process. If the surface temperature uniformity of the glass is not well ensured before the rapid cooling process, a serious quality problem occurs during the rapid cooling process.
As mentioned in the background, in a related art, forced convection is generally provided in the heating section. In this manner, when the glass is softened at a high temperature, the airflow with a certain speed and pressure to will form streaks on the surface of the softened glass. This problem is solved in the present application where horizontal parallel airflow is created in the soaking section.
In addition to the preceding disadvantage of the forced convection, for direct-fired gas heating, the high-speed airflow in the furnace seriously affects the porous medium burners.
The thermal conductivity of the glass is very low. To homogenize the temperature of the glass within a specified period of time on the premise that the productivity is satisfied, it is necessary to improve the convective heat transfer efficiency/capability. For the airflow soaking technology, to ensure the temperature uniformity of the product, one of the following two conditions must be satisfied:
Fully turbulent airflow requires a powerful fan. Such airflow is not conducive to the stability of light and thin glass on drive rollers 101. Moreover, impurities on the insulation materials in the furnace and impurities in the furnace chamber are carried by the turbulent airflow and cover the entire furnace chamber and the surface of the glass, causing the quality of the surface of the glass to be out of control.
In the present application, the soaking furnace section 300 for forced convection of horizontal parallel airflow delivered in the subsequent after the heating furnace section 200, which serves as the final heating and temperature adjustment process. The required power in this process is far smaller than the power of the heating section. Therefore, the power output of the heater 320 is required to respond fast and continuously adjustable. In the present application, the heat source of the soaking furnace section 300 is an electric tubular heater integrated box that is plugged into the air duct.
In some embodiments of the present application, referring to
In one embodiment, the four sections of air ducts 310 are disposed in the receiving cavity 350. Each air duct 310 has air outlets 313 and air suction ports 314. The air outlets 313 are respectively disposed above and below the drive rollers 101 and at a first end 1011 of the drive rollers 101 along the radial direction of the drive rollers 101 to enable air blown out from the air outlet 313 to reach the first end 1011 of the drive roller 101, blow out from the gap between adjacent drive rollers 101, and blow over the upper and lower surfaces of the glass 20 along a direction parallel to the drive roller 101s.
In an embodiment, the air suction ports 314 are respectively disposed above and below the drive rollers 101, and adjacent to a second end 1012 of the drive rollers 101 and each of the air suction ports 314 is configured to suck the gas blowing over the upper and lower surfaces of the glass 20.
In the soaking furnace section 300 of the present application, air blown from the air outlet 313 can reach the first end 1011 of the drive roller 101, blow out from the gap between adjacent drive rollers 101, and blow over the upper and lower surfaces of the glass 20 parallel to the drive roller 101. In this manner, air can sweep across horizontally in parallel to the upper and lower surfaces of the glass 20to complete heat exchange with the glass 20. This horizontally parallel soaking mode can greatly improve the non-uniform heating temperature of the surface of the workpiece.
In some embodiments of the present application, each air duct 310 includes a centrifugal fan 311 and an air duct body. The centrifugal fan 311 is configured to rotate to suck the air in and to throw the air out, so that the air flows in the air duct body, is blown out from the gap between adjacent drive rollers 101, and sweeps across horizontally in parallel to the upper and lower surfaces of the glass 20 to complete heat exchange with the glass 20. In an embodiment, the air duct body includes an air-suction air duct section 3122 and an air-blowing air duct section 3121. A first end of the air-blowing air duct section 3121 is connected to the outlet of the centrifugal fan 311. An air outlet 313 is disposed at a second end of the air-blowing air duct section 3121. A first end of the air-suction air duct section 3122 is connected to the inlet of the centrifugal fan 311. A second end of the air-suction air duct section 3122 is provided with an air suction port 314.
A first end of the air-blowing air duct section 3121 is connected to the outlet of the centrifugal fan 311. An air outlet 313 is disposed at a second end of the air-blowing air duct section 3121. When the centrifugal fan 311 rotates at a high speed, air is sucked in from the inlet of the centrifugal fan 311, is thrown out in the tangent direction into the air-blowing air duct section 3121, passes through the air-blowing air duct section 3121, and reaches the air outlet 313. Air blown out from the air outlet 313 reaches the first end 1011 of the drive roller 101, collides with the sidewall surface of the first end 1011, changes direction, is blown out from the gap between the adjacent drive rollers 101, and blow over the upper and lower surfaces of the glass 20 in parallel to the drive rollers 101, thereby realizing horizontally and parallelly soaking the workpiece.
In an embodiment, referring to
In an embodiment, the air-blowing air duct section 3121 includes a first air duct portion 31211 and a second air duct portion 31212. The first air duct portion 31211 is parallel to the drive roller 101. The second air duct portion 31212 is perpendicular to the drive roller 101. The air outlet 313 is disposed on a sidewall surface of the second air duct portion 31212 facing the first end 1011 of the drive roller 101.
In an embodiment, referring to
In an embodiment, a first end of the first air duct portion 31211 is connected to the outlet of the centrifugal fan 311, a second end of the first air duct portion 31211 is connected to the inlet of the second air duct portion 31212, and a second end of the second air duct portion 31212 is the air outlet 313.
In an embodiment, the first air duct portion 31211 and the second air duct portion 31212 are square.
In some implementations, the first end of the first air duct portion 31211 communicating with the outlet of the centrifugal fan 311 has a small size, and the second end of the first air duct portion 31211 has a large size, so that the first air duct portion 31211 is approximately trumpet-shaped. The size of the inside channel of the second air duct portion 31212 is set according to the length of the soaking furnace section 300. The size of the inside channel of the second air duct portion 31212 determines the coverage width of the blown air, that is, the width of the air blowing over the workpiece.
In some embodiments of the present application, the inlet of the centrifugal fan 311 is disposed below the impeller of the centrifugal fan 311.
In some embodiments of the present application, the soaking furnace section 300 also includes a heater 320. The heater 320 is configured to heat air that has completed heat exchange to a preset temperature. The heater 320 is disposed below the impeller of the centrifugal fan 311 so that air sucked in by rotation of the impeller passes through the heater 320 and then enters the impeller of the centrifugal fan 311. The air blowing over the upper and lower surfaces of the workpiece completes heat exchange with the workpiece. At this time, the temperature of the air decreases, and the air passes though the heater 320 and can be heated to the preset temperature again.
The temperature of such air heated by the heater 320 is not uniform. In this embodiment, air heated by the heater 320 is sucked into the centrifugal fan 311 again and stirred by the impeller of the centrifugal fan 311. In this manner, the non-uniform air that has been heated by the heater 320 is fully stirred and dispersed so that the temperature of the air is homogenized. The homogenized air is sucked into the air duct 310 again by the centrifugal fan 311 rotating at high speed to equalize the heat of the workpiece, thereby making cyclic heat-balance possible, and thus facilitating energy conservation and emission reduction.
Referring to
In some embodiments of the present application, the first end of the air-suction air duct section 3122 of the soaking furnace section 300 is connected to the inlet of the centrifugal fan 311, and the air suction port 314 is disposed at the second end of the air-suction air duct section 3122.
In some embodiments of the present application, the heating part 321 of the heater 320 is disposed in the air-suction air duct section 3122.
The heating part 321 of the heater 320 is disposed in the air-suction air duct section 3122 so that air blowing over the upper and lower surfaces of the glass 20 can be heated by the heating part 321 of the heater 320 when passing through the air-suction air duct section 3122, thereby improving the heating efficiency and reducing the energy consumption.
The first end of the air-suction air duct section 3122 of the soaking furnace section 300 is connected to the inlet of the centrifugal fan 311, and the air suction port 314 is disposed at the second end of the air-suction air duct section 3122. Thus, air blowing over the upper and lower surfaces of the glass 20 can pass through the air-suction air duct section 3122 to reach the inlet of the centrifugal fan 311, and is sucked into the centrifugal fan 311, and then can be stirred again and circulated to soak. In some embodiments of the present application, the soaking furnace section 300 includes multiple air ducts 310. The air ducts 310 are spaced apart from each other along the rotation direction of the workpiece.
In an embodiment, referring to
In some embodiments of the present application, the soaking furnace section 300 is divided into a soaking-section upper furnace portion 330 and a soaking-section lower furnace portion 340. The soaking-section upper furnace portion 330 is disposed above the drive rollers 101. The soaking-section lower furnace portion is disposed below the drive rollers 101.
The preheating furnace section 100, the heating furnace section 200, and the soaking furnace section 300 are each divided into an upper portion and a lower portion, facilitating mounting or removal of the drive rollers 101 and the maintenance of the device. In an embodiment, the drive rollers 101 may be ceramic rollers common in the art.
In some embodiments of the present application, each of the preheating furnace section 100, the heating furnace section 200, and the soaking furnace section 300 has a furnace section lifting apparatus 400. The furnace section lifting apparatus 400 is connected to the upper portion and configured to lift the upper portion.
In some embodiments of the present application, a glass tempering method is provided. The method is applied by the glass tempering furnace 10 of any previous embodiment to temper the glass.
In some embodiments of the present application, the method applied by the glass tempering furnace 10 of any previous embodiment to temper the glass 20 includes the following steps:
The beneficial effect of the glass tempering method of the present application is as follows: The method uses the preceding glass tempering furnace to temper glass, so that the method can heat the glass rapidly and evenly. The method is applicable to not only tempering of ordinary glass, but also tempering of coated glass and Low-E glass.
The glass that has been heated up and has uniform temperature can enter the next process.
Referring to
According to analysis, a porous medium burner cannot be applied to a high temperature scenario for the following reasons:
Therefore, in terms of a burner based on the porous medium combustion technology in the related art, the part of the burner facing the furnace is typically a metal frame. After working for a long time, the frame undergoes various degrees of deformation. Such metal frame may lead to a serious consequence in a high-temperature scenario, so the burner cannot be used in a high-temperature furnace. To address the problem that a porous medium burner of the related art can be applied to only a low or medium furnace temperature and mostly applied to only a low furnace temperature and to broaden the application scope to a high-temperature field, the present application provides a porous medium burner applicable to a high furnace temperature environment whose original structure with a metal skeleton with cooling function is protected.
Additionally, limited by the characteristics of “premixed combustion” and “porous medium combustion”, in the related art, the power adjustment ratio of a porous medium burner (the ratio of the maximum power to the minimum power for a stable operation of the burner) is typically fixed or has a narrow adjustment range. In other words, the gas flow rate remains constant, also limiting the applicability of the burner.
In the related art, the methods and characteristics of power adjustment of a thermal apparatus based on a porous medium burner are as follows:
Therefore, it is required to improve the adjustment capability of a burner from a design perspective of the burner to solve the problem of fixed power and small power adjustment ratio of the burner in related technologies.
The infrared burner 210 of this embodiment includes a housing. The housing has a chamber, an air inlet 2112 and a heat release port 2113, the air inlet 2112 connected to the chamber, and the heat release port 2113 connected to the chamber. A premixing area 2115, an anti-flashback area 218, and a combustion area 219 are disposed in sequence in the chamber along the air inlet direction from the air inlet 2112 to the heat release port 2113.
The housing includes an inner cylinder 2114 and a cover plate 2111 having an air inlet 2112. The air inlet 2112 is configured to input mixed combustion gas formed of gas and combustion-support air. One or more air inlets 2112 may be provided. For example, two or three air inlets 2112 may be provided. The cover plate 2111 is disposed at one end of the inner cylinder 2114 to form the chamber. In this embodiment, the housing is made of metal, the space in the inner cylinder 2114 is cylindrical, the housing and the cover plate 2111 are square, one air inlet 2112 is provided, and is located at the center of the cover plate 2111, and the inner cylinder 2114 is fastened to the cover plate 2111 by a flange and a sealing gasket.
The main function of the premixing area 2115 is to mix and disperse the mixed combustion gas formed of gas and air entering through the air inlet 2112 so that the mixed combustion gas is further mixed and dispersed before uniformly entering the anti-flashback area 218. A gas distribution plate having distribution holes are disposed in the premixing area 2115. The gas distribution plate is connected to the housing. The orthographic projection of the air inlet 2112 is located on the gas distribution plate. In this embodiment, the orthographic projection is a projection along an air inlet direction, and the orthographic projection of the air inlet 2112 is located at the center of the gas distribution plate. After passing through the gas distribution holes of the gas distribution plate, the mixed combustion gas can be evenly distributed to the premixing area 2115 and then evenly distributed to a porous medium material layer 214 through the gas channels of a heat-insulating material layer so that the mixed gas can be uniformly burned in the porous medium material layer 214, thereby improving the uniformity of combustion and heating.
The main function of the anti-flashback area 218 is to separate the premixing area 2115 from the combustion area 219 to prevent flareback. The anti-flashback area 218 is filled with a heat-insulating material layer with gas channels. The heat-insulating material layer further fully mixes and uniformly distributes the mixed combustion gas entering from the premixing area 2115, and then conveys the mixed combustion gas to the combustion area 219 for combustion. The heat-insulating material layer has gas channels. The thickness of the heat-insulating material layer along the air inlet direction ranges from 100 mm to 200 mm. In general, the heat-insulating material layer consists of at least two layers of heat-insulating material plates 213 arranged in a stacked manner along the air inlet direction. The thickness of a single layer of heat-insulating material plate 213 ranges from 50 mm to 100 mm. Gas channels of any two adjacent layers of heat-insulating material plates 213 are correspondingly interconnected to form complete gas channels. In this embodiment, the heat-insulating material layer consists of two layers of heat-insulating material plates 213. The gas channels of the two layers of heat-insulating material plates 213 are interconnected to form complete gas channels. The complete gas channels run along the air inlet direction and arranged at the center of the heat-insulating material layer.
By machining through holes in the thickness direction of the heat-insulating material layer, the premixed gas is allowed to enter the porous medium material through these through holes. On the one hand, uniform distribution of airflow is required to be achieved by the through holes. On the other hand, the diameter and number of the through holes need to satisfy related combustion rules. In embodiments of the present application, the aperture ratio for gas channels on the heat-insulating material layer is 1% to 5%.
The heat-insulating material layer is composed of refractory material capable of withstanding temperatures from 900° C. to 1400° C., such as a ceramic plate, and may be selected according to actual requirements. This is not limited here. The diameter of each gas channel in the heat-insulating material layer ranges from 1.5 mm to 4 mm. This is not limited. In this embodiment, the diameter of each gas channel in the heat-insulating material layer is 3 mm. Moreover, the depth-to-diameter ratio of each gas channel is relatively large, typically 30:1 to 80:1, to enhance the anti-flashback effect.
When the depth-to-diameter ratio (depth/diameter) of each gas channel in the heat-insulating material layer of the anti-flash back area 218 is large enough, it is possible to decrease the gas and air simultaneously or increase the gas and gas simultaneously to adjust the power of the burner. A larger depth-to-diameter ratio can increase the pressure of the mixed combustion gas, so that making the gas flow rate is higher than the flame propagation speed without worrying about the occurrence of tempering phenomenon, and at the same time, high combustion efficiency and low pollution emission can be achieved.
The main function of the combustion area 219 is combustion. A porous medium material layer 214 is disposed in the combustion area 219. The gas channels of the heat-insulating material layer communicate with both the premixing area 2115 and the porous medium material layer 214. The porous medium material layer 214 is configured to receive and burn the mixed combustion gas mixed and dispersed in the heat-insulating material layer. The temperature of the opposite side contacting with the premixing area 2115 of the heat-insulating material layer is lower than the ignition point of the combustion gas. In this embodiment, the porous medium material layer 214 is disposed in the central area of the heat-insulating material layer. The porous medium material layer 214 has a combustion surface facing the heat release port 2113 and configured to output gas and heat. There is a certain distance between the combustion surface and the heat release port 2113. A heat-insulating material support layer 2153 configured to support heat-insulating material is provided at a position (combustion area 219) in the chamber facing the heat release port 2113. The heat-insulating material support layer 2153 has a heat release channel corresponding to the porous medium layer 214. The heat release channel communicates with the heat release port 2113.
The material of the porous medium material layer 214 includes, but is not limited to, silicon carbide (SiC). SiC has a radiation rate of about 0.9, much higher than that of a general metal alloy heating material, leading to a better radiation heating effect. Of course, the material of the porous medium material layer 214 may be another refractory material, without limitation here. The structure of the porous medium material layer 214 includes, but is not limited to, a foam structure, a honeycomb structure, or an array structure.
The porosity of the porous medium material layer 214 is 50% and 90%. Based on this, the thickness of the porous medium material layer 214 is controlled between 15 mm and 30 mm.
By controlling key data of the heat-insulating material layer and the porous medium material layer 214, the adjustment ratio of the burner is achieved from very small to a high range of 1:1 to 5:1.
According to the preceding description, the background radiation of the furnace at a high temperature is quite strong. This means that the radiation power from the furnace to the burner is also considerable. This part of radiation power to the burner is as follows: the side of the burner facing the furnace withstands high temperature and heat input. As the housing of the burner mostly uses a heat-resistant steel frame, the excellent thermal conductivity of steel determines the rapid transfer of heat throughout the metal frame of the burner. Even if the metal frame of the burner is made of heat-resistant alloy materials, the metal undergoes “creep” at a high temperature. This deformation is irreversible. Moreover, the high-temperature environment can weaken the heat insulation effect of the anti-flashback area 218, thereby reducing the anti-flashback effect. Therefore, it is necessary to maintain the overall temperature of the housing (metal frame) and the anti-flashback area 218 at a controlled level.
To control the overall temperature of the housing, a cooling interlayer 212 for receiving a cooling medium is disposed around the housing, and the cooling interlayer 212 at least wraps part of the premixing area 2115, part of the anti-flashback area 218, and part of the combustion area 219. In an embodiment, an outer cylinder 2121 is sleeved on the inner cylinder 2114, and a cooling interlayer 212 is formed between the inner cylinder 2114 and the outer cylinder 2121. In this embodiment, the inner cylinder 2114 and the outer cylinder 2121 are each cylindrical. The outer cylinder 2121 wraps most of the premixing area 2115 of the inner cylinder 2114, the entire anti-flashback area 218, and most of the combustion area 219, and only does not wrap areas at the top and bottom of the inner cylinder 2114. The two ends of the outer cylinder 2121 are each welded to the inner cylinder 2114 by a sealing plate.
In the working process of the burner, an air-gas mixture obtained before entering the burner or an air-gas mixture mixed in the premixing area 2115 pauses in the premixing area 2115 for a short time and then enters the porous medium material layer 214 through the gas channel of the heat-insulating material layer so as to be burned. As a container for combustible gases, it is necessary to ensure that the temperature at any point in the premixing area 2115 is not too high; otherwise, a combustion phenomenon, namely flashback, will occur in the premixing area 2115.
To promptly cool down the premixing area 2115, the cooling interlayer 212 is provided with a cooling inlet 2122 and a cooling outlet 2123 of the cooling medium. The cooling inlet 2122 and the cooling outlet 2123 are adjacent to the air inlet 2112.
In the present application, different cooling media are selected according to different furnace temperature requirements. In an embodiment, the furnace temperature is required to be below 700° C., and gas is used as the cooling medium. Referring to
In an embodiment, when a furnace temperature of 700° C. to 1150° C. is required and when the furnace temperature is in the high-temperature range greater than 1000° C., a liquid cooling technology should be used. The cooling medium may be water or oil to achieve stable control of the overall temperature of the burner housing. Referring to
During the operation of the burner, due to the different thermal conductivities of materials, heat conducted from the heat-insulating material plate 213 to the inner cylinder 2114 is cooled by the cooling medium in the cooling interlayer 212, thus avoiding deformation of the housing of the burner at a high temperature. At the same time, a difficulty in achieving a high adjustment ratio is to prevent flashback when the mixed combustion gas flows at a low speed, ensuring that the flow rate of the mixed combustion gas is always higher than the flame propagation speed. The contact surface between the heat-insulating material plate 213 and the porous medium material layer 214 is maintained at a low temperature, and the temperature is lower than the ignition point of the gas. When the power of the burner is reduced by reducing the flow rate of the mixed combustion gas, the low temperature can reduce the flame propagation speed. Even if the flow rate of the mixed combustion gas is small, the anti-flashback effect can be maintained, thereby increasing the adjustment ratio of the burner.
To ensure real-time monitoring of the temperature of the premixing area 2115, the glass tempering furnace also includes a thermocouple 2151 inserted in the premixing area 2115. The probe end of thermocouple 2151 is adjacent to the inner wall of the premixing area 2115.
For heat insulation and heat preservation of the housing, a heat preservation material layer 2152 is disposed around the cooling interlayer 212.
To support the housing, the infrared burner 210 also includes a bottom heat-insulating panel 2154 for supporting the housing and the cooling interlayer 212. The bottom heat-insulating panel 2154 has a heat release hole corresponding to the heat release port 2113, which does not affect the dissipation of heat.
A bottom panel 2156 made of metal is generally provided below the heat-insulating material support layer 2153 of the burner, there is typically a metal for support. Due to the bottom panel 2156 faced with a high temperature inside the furnace is heated to expend and produce a high temperature creep effect, which may cause the bottom panel 2156 to warp. Once the deformation is excessive, the heat-insulating material support layer 2153 is damaged by the force caused by the deformation, causing the porous medium material layer 214 carried on the heat-insulating material support layer 2153 to become unstable. Therefore, a stiffener 2157 is added in this embodiment to weld and reinforce the bottom panel 2156 of the burner. One part of the stiffener 2157 is welded to the inner cylinder 2114, and the other part of the stiffener 2157 is welded to the bottom panel 2156.
In this embodiment, the heat-insulating material layer is closely adhered to the porous medium material layer 214. A pressing mechanism 2155 arranged along the air inlet direction is disposed in the premixing area 2115. A first end of the pressing mechanism 2155 is connected to the housing. A second end of the pressing mechanism 2155 abuts against the heat-insulating material layer and presses the heat-insulating material layer to ensure that the heat-insulating material layer remains tightly adhered to the porous medium material layer 214. Three pressing mechanisms 2155 are provided. The three pressing mechanisms 2155 are equally spaced apart around the axis of the housing. In an embodiment, four pressing mechanisms 2155 are provided. The four pressing mechanisms 2155 are disposed at the four corners of the housing. The pressing mechanism 2155 enables the heat-insulating material layer to be always tightly adhered to the porous medium material layer 214, avoiding gaps between the heat-insulating material layer and the porous medium material layer 214 due to thermal expansion of the burner in a working process, and thus avoiding poor combustion caused by rapid heat diffusion due to the gaps.
The working process of each infrared burner 210 is as follows:
The premixed gas of the combustion-supporting air and the gas enters the chamber through the air inlet 2112 and stops in the premixing area 2115 for a short time. The premixed gas is mixed in a turbulent manner in the premixing area 2115 while cooling the surrounding wall to a certain extent.
Premixed gas enters the porous medium material layer 214 along gas channel in the heat-insulating material layer and completes combustion in the porous medium material layer 214. Since gas is ignited in the beginning, as premixed gas enters continuously, the combustion process in the porous medium material layer 214 continues, and the porous medium material in the normal working state presents an infrared state.
The cooling medium enters the inner cylinder 2114 through the cooling inlet 2122, moves one circle around the inner cylinder 2114 in the cooling layer 212 and is discharged through the cooling outlet 2123 to control the overall temperature of the housing. The thermocouple 2151 monitors the temperature of the premixing area 2115 in real time to evaluate the cooling effect of the cooling medium.
In the description of the specification, the description of reference terms such as “some embodiments” and “other embodiments” is intended to mean that features, structures, materials, or characteristics described in conjunction with such embodiments or examples are included in at least one embodiment or example of the present application. In the specification, the illustrative description of these terms does not necessarily refer to the same embodiment or example. Moreover, the described features, structures, materials, or characteristics may be combined in an appropriate manner in one or more embodiments or examples.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211358216.6 | Nov 2022 | CN | national |
| 202222929439.5 | Nov 2022 | CN | national |
| 202322399577.1 | Sep 2023 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2023/126858 | 10/26/2023 | WO |
